Relevant to the field of inquiry, is prior art featuring inclined body support means, drawn and/or pushed upon rail or rails with various leveraging systems. Together they comprise a special group of gravity sensitive machines that support the body and offer traction type exercise cycles. Of the art reviewed, one apparatus, proposed by Randy Coyle in U.S. Pat. No. 4,176,836, issued on Dec. 4, 1979, describes a means for introducing variable resistance to the exercise cycle. Mr. Coyle's discrete curved incline served the variable resistance objective well and correctly identified the benefits of matching machine mechanics with body force curves. Unfortunately, if generalized to broader applications, as might be envisioned in machines that exercise both arms and legs, the radial incline pattern presents body containment problems. Tests conducted by the applicant on total body prototypes employing the curved rail principle, indicate that, even when a seat is provided, some means of seat positioning is required to counteract tip out at the more vertical stages of sled ascent. Other, lesser problems associated with the curved rail design pertain to secondary forming defects. Curved structural elements are expensive and more subject to contour and cross section irregularities, wrinkling, and buckling than are straight line, mill formed elements.
The present invention envisions a machine design that offers variable resistance benefits, absent the discussed body containment and forming difficulties. A special series of sequential drawings, FIGS. 2A, 2B, 2C and 3A, 3B and 3C companion the summary to illustrate the essential elements of two distinct kinetic exercise cycles and to identify the essential structural and operational uniqueness of the present invention.